This invention relates to an electrical connector whose contacts are connected to connection wires in an insulation-piercing system, and more particularly to an arrangement of contacts and configuration of connection wire receiving portions of a connector main body and urging portions of a cover.
There have been many ways for connecting wires and contacts of a connector, such as soldering, wrapping, crimping and insulation-piercing method and the like. In the insulation-piercing method among these ways, a connection wire 3 is forced by means of a cover B into the tail 2 of a contact fixed to an insulating support block 1 of a connector main body A. The tail 2 has a piercing groove 2a at its center and oblique blades 2b on both sides thereof as shown in FIG. 1a. As a result, the coating 3a of a connection wire 3 is cut by the oblique blades 2b to the core 3b of the connection wire 3. Thereafter, the connection wire 3 is forced into the piercing groove 2a so that the contact tail 2 is connected to the core 3b of the connection wire 3.
With development of electronics, electronic parts have been required to be highly dense and miniaturized year by year. According to these requirements, an insulation-piercing connector has been proposed in Japanese Patent Application No. 63-253,419 as shown in FIG. 2a and 2b. FIG. 2a illustrates a connector main body A in a perspective view, while FIG. 2b illustrates in a perspective view a cover B of the connector turned upside down in order to clearly show its characteristic parts.
Referring to FIGS. 2a and 3a, the connector main body A includes a plurality of insulation-piercing contact tails (referred to hereinafter as "contact tails") 2 arranged in first, second, third and fourth rows 2A.sub.1, 2A.sub.2, 2B.sub.1 and 2B.sub.2 in parallel and spaced from each other. Moreover, connection wire support inclined bases 3C and 3D for supporting connection wires are arranged on the upper surface of the insulating support block 1 so that the inclined bases 3C and 3D are within the width of the contact tails, and surfaces of the inclined bases 3C and 3D are inclined in reverse directions. Between two inclined bases 3C inclined in the same direction is arranged one inclined base 3D inclined in the reverse direction which is positioned at the center of a contact tail forming the first row 2A.sub.1.
Moreover, the contact tails forming the second row 2A.sub.2 are so fixed to the insulating support block 1 that centers of these contact tails are positioned at centers between the contact tails forming the first row 2A.sub.1, and within the width of each of the contact tails are arranged two inclined bases 3D inclined in the same direction and one inclined base 3C inclined in the reverse direction. Further, the contact tails forming the third and fourth rows 2B1 and 2B2 are fixed to the insulating support block 1 so as to be shifted by one inclined base 3C and extend over two inclined bases 3D so that the contacts of the third and fourth rows are staggered or alternately shifted. Heights and inclinations of the inclined bases are so selected that only piercing grooves of the contact tails 2 to be connected with the connection wires 3 project upwardly beyond the inclined bases, whereas other contact tails 2 do not project beyond the inclined bases.
Referring to FIG. 2b, the cover B includes inclined bases 3E and 3F for supporting connection wires, which are adapted to be inserted between the inclined bases 3C and 3D of the connector main body A and inclined in direction reverse to the inclined directions of the inclined bases 3C and 3D. The cover B further includes receiving slots 5 for receiving the contact tails 2 projecting from the connector main body A. Reference numerals 4A and 4B denote hooks and anchoring members for locking the connector main body A and the cover B.
With this arrangement, connection wires, for example, connection wires 3A and 3B of a flat cable 3 (FIG. 3b) are arranged on the surfaces of the inclined bases 3C and 3D, and the cover B is arranged over the connector main body A and forced toward the main body A. As a result, the flat cable 3 is connected to the contacts 2 forming the contact tail rows 2A.sub.1, 2A.sub.2, 2B.sub.1 and 2B.sub.2 as shown in FIGS. 1b and 3a.
However, the above insulation-piercing connector of the prior art involves the following problems to be solved.
FIGS. 4a, 4b and 4c illustrate a relationship in height between the contact rows 2A.sub.1, 2A.sub.2, 2B.sub.1 and 2B.sub.2 of the contact tails 2 of the prior art connector shown in FIGS. 2a and 2b.
(1) As shown in FIG. 4a illustrating the assembled contact main body A and cover B, piercing depths are different as indicated by a and b between the contact rows 2A.sub.1 and 2B.sub.2 arranged on the outer side and the contact rows 2A.sub.2 and 2B.sub.1 on the inner side. Therefore, there is a difference in piercing force by which the core 3b of the connection wire is forced into the piercing groove 2a. Consequently, when a connector is miniaturized, the contacts on the inner side become short resulting in less reliability in connection.
(2) When the flat cable 3 shown in FIG. 3b is arranged on the inclined bases 3C and 3D of the connector main body, and the cover B is then arranged thereon and forced toward the connector main body A. As a result, the connection wires 3A are pushed upwardly and connection wires 3B are pushed downwardly so that the contact tails pierce into the connection wires 3A and 3B. In the prior art, a torn length c of the flat cable 3 shown in FIG. 4c is long. Therefore, this connector does not fulfill the requirement of miniaturization.